Circuit breaker



March 14, 1933. H. G. BAXTER I CIRCUIT BREAKER Filed March 18, 1931 2 Sheets-Sheet March 14, 1933. H. G. BAXTER u CIRCUIT BREAKER Filed March 18, 1931 2 Sheets-Sheet 2 INVENTOR Harold @Baxter @7/@VQAM/ ATTORN EY Patented Mar. 14, 1933 UNITED STATES PATENT OFFICE HAROLD G. BAXTER, 0F BALDWIN, 'N EW YORK, ASSIGNOR T0 WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION 0F PENNSYLVANIA CBC'U IT BBEAKER Application led March 18, 1981.

My invention relates to circuit-breakers and particularly to circuit-breakers for use as main circuit-controlling switches for circuit-breakers of a distributing panel-board.

An object of my invention is to provide a circuit-breaker that shall be trip-free of the operating handle and wherein the parts constituting the circuit-breaker shall beso d1sposed that the height of the circuit breaker 1s reduced to a minimum and may be conveniently mounted in a shallow-type distributing panel-board housing.

Another object of my invention is to provide a relatively heavy-duty circuit-breaker for distributing panel-boards wherein. the circuit-interruptin device shall comprise a bridging switch o the laminated type that may be rotated .into and out of conductlve engagement with spaced contact members with a snap action and wherein a doublebreak in the circuit shall be made 'when the circuit-breaker opens. l

A further object of my invention is to provide a circuit-breaker for distributing panel boards having the above-noted characteristics, wherein the parts of the circuit-breaker may be stamped from sheet metal and be readily assembled to constitute a rugged and inexpensive circuit-breaker structure.

These, and other objects that will be made apparent throughout the further descrlption of my invention, are attained by means of the apparatus hereinafter described, and illustrated in the accompanying drawlngs, wherein,

Figure 1- is a side-elevational view of a circuit-breaker embodying features of my invention, the parts being shown in closed position;

Fig. 2 is an enlarged transverse section on the line II--II of Fig. 1, showing parts of the circuit breaker in end elevation;

Fig. 3 is a side elevational view, similar to that of Fig. 1, showing the parts in the positions they occupy when the circuitbreaker has been opened by the currentresponsive trip mechanism, and

Fig. 4 is a similar view showing the parts in the positions that they occupy when the Serial No. 523,477.

circuit-breaker has been opened by manual operation.

Referring to the drawings, the circuitbreaker includes an insulating base 5 upon which contact members 6 and 7 are mounted, the former being secured directly to the outer face of the base, and the latter being mounted on the base and having a contact portion 8 extending into the lane parallel to the base and spaced therei'om, as indicated in Fig. 1.

A pair of sheet-metal frame members 9 are secured to the base and serve to support a laminated bridging switch member 11 that consists of a plurality of flat metal leaves disposed in the manner indicated in Fig. l and mounted upon a -switch arm 12 that is provided with laterally extending pivot shafts 13 that are mounted for rotation in bearing openings 14 in the frame members 9. f

A second air of frame members 15 are mounted on t e base exteriorly of the frame members 9 to pivotally support an operating handle 16 that is of U-shape and is mounted for rotation about a pivot shaft 17 that is journaled in the frame members 15, as indicated in Figs. l and 2. Limited oscillatory movement of the operating handle is permitted between the stops 18 and 19 on the frame members 15, the operating handle being movable between the full-line closed position A and the open position B, indicated by broken lines in Fig. 1.

A cradle member 21, having a central latch member 22 and a pair of spaced arms 23, is disposed between the side arms 24 of the operating handle 16, and normally eX- tends outwardly from the base in a direction normal to the plane thereof. By reason of this arrangement of the cradle, which is pivoted for rotative movement about a shaft 20, mounted on the frame members 9, rotary movement thereof, within its limits of movement, does not move parts thereof beyond the position occupied by the outer extremities of the'arms and, consequently, the overall dimensions of the enclosing housing 24 need not extend beyond the space of the outer ends ofthe arms.

The cradle 21 is pivotally connected to the arm 12 of the switch member 11 by means of a pair of toggle links 25 and 26 that are connected to each other by a knee pivot 27 and to the cradle 21 and the switch arm 12, respectively, by pivot shafts 28 and 29.

A tension spring 31'is pivotally connected, at one end, to the operating handle 16 by means of an eyelet 33, and the other end of the spring is pivotally Aconnected to the knee pivot 17 of the toggle, and, when the operatinfr handle is in the closed position, indicated in Fig. 1, the spring normally biases the cradle 21, through the medium of the link 25, in a counterclockwise direction, but movement of the cradle is restrained by means of a latch clip 34 mounted on a bimetal thermal current-responsive element 35 which releasably retains the cradle in the operative position, as shown in Fig. 1.

It will be understood that the bimetal thermal element 35 is of the usual U-shape and is connected in series with the contacts of the circuit-breaker in such manner that current controlled by the circuit-breaker also .flows through the bimetal element. In the case of a severe overload or short-circuit condition, occurring in the circuit, the bimetal element deflects the latch cli 34 toward the left and releases the crad e 21, so that the spring 31 may contract and move the cradle, in a counter-clockwise direction, to the position shown in Fig. 3, and incidentally, collapse the toggle so that the switch member 11 is moved to the open position shown in Fig. 3, with a snap action, due to the suddencontraction of the spring 31. The operating handle 16 is moved, by the spring 3l, to an intermediate position indicated in Fig. 3, and this movement of the operating handle serves as an indication that the circuit-breaker has been tripped to open position, in response to an overload or short-circuit condition.

In order to restore the circuit-breaker to the closed position indicated in Fig. 1, it is first necessary to return the cradle 21 to its latched operative position and this is accomplished by moving the operating handle 16 in a clockwise direction. A cross bar 36 on the handle engages extensions l37 on the cradle arms 23 and imparts suiicient clockwise rotative movement to the cradle to move the latch arm 22 above the latch clip 34. After this has been accomplished, the parts 'occupy the open circuit-breaker position shown in Fig. 4 wherein the cradle is in latched operative position and the switch arm 11 is 1n the open position.

To close the circuit-breaker, the operating handle 16 is moved in a counter-clockwise direction and, when the upper end of the ring 31 is moved past a center line C (Fig. the toggle link 25 will be turned about the pivot shaft 28 in a clockwise direction,

thereby causing the switch member 11 to be moved in a counter-clockwise direction to the closed position shown in Fig. l, and the toggle links 25 and 26 to be moved to the overcenter made position, as indicated in Fig. 1. Since the cradle cannot move at this time, the toggle links serve to bias the switch member 11 into engagement with contact members 6 and 8 with sufiicient pressure to actually bend the leaves of the laminated switch member l1. Thus, a good conductive contact is maintained, and it will be noted that, when the switch arm is moved to the open position, the circuit is interrupted at two points, thereby increasing the circuit-rupturing capacity of the circuitbreaker.

The supporting' frames 9 are provided with stop members 38 and 39 which serve to limit the movement of the knee pivot 27 of the toggle.

It is a parent from the foregoing that a rugged, ieavy-duty circuit-breaker is provided that may be inexpensively made by stamping the major portions of the parts from sheet metal and that, by reason of the arrangement of the parts, the height of the circuit-breaker is reduced to a minimum.

Since my invention may be variously modified without departing from its spirit and scope, I desire that only such limitations shall be placed thereon as are embodied in the prior art or are set forth in the appended claims. f

I claim as my invention:

1. The combination with a circuit-breaker having a base, a movable switch member thereon, a cradle and a toggle cooperating with the switch member and the cradle for releasably retaining the switch member in closed position, of a. latch member on the cradle movable toward the base when the cradle is released, and a current-responsive member cooperating with the latch member for releasably retaining it in latched position.

2. A circuit breaker comprising a base, circuit controlling means pivotally mounted on the base for rotation in a plane substantially normal to the plane of the base, a cradle pivotally mounted on the base having laterally spaced arms disposed on opposite sides of the circuit controlling means and permitting movement of the latter between said laterally spaced arms, toggle links connecting the cradle and the circuit controlling means and pivotally connected to the4 arms of the cradle, and a current-responsive member cooperating with the cradle for releasably retaining it in operative set posit1on.

3. A circuit breaker comprising a base,4 a contact actuating member mounted on the base for movement in a plane substantially normal to the plane of the base, a cradle pivotally mounted on the base and having spaced arms disposed on opposite sides of the contact actuating member to permit movement of the latter between the spaced arms, a pair of toggle links connecting the cradle and the contact actuating member, acurrent-responsive member cooperating with the cradle for releasably retaining itin operative set position, an operating handle pivotally mounted on the base and having a pair .of spaced arms straddling the cradle and permitting of movement thereof between the spaced arms of the said handle, and means on the handle for returning the cradle to set position.

4. In a circuit interrupter, means movable to open and close the circuit, a lever pivoted at a point intermediate its ends, a pair of toggle links having one end of one link pivoted to said means to open and close the circuit and one end of the other link pivoted on said lever adjacent one end thereof, releasable means for engaging the other end of said lever to releasably hold it in a set position, and operating means for moving said toggle links to actuate said means to open and close the circuit while said lever is held in its set position.

5. In a circuit interrupter, a switch member movable to opened and to closed positions, a bell-crank lever pivoted at a point intermediate its ends, a pair of toggle links pivoted to each other forming the knee of the toggle and having one end pivoted to said switch member and the other end pivoted to one end of said bell-crank lever, a handle member, a spring connected between said handle and the knee of said pair of toggle links for transmitting movement of said handle to move said toggle links to actuate the switch member from open to closed position, a releasable latch for holding the other end of said bell-crank lever in a set position, said latch being releasable in response to the current flow through the circuit interrupter, and said toggle links being collapsible upon the release of said bell-crank lever to move the switch member to o ened position.

In testimony whereo I have hereunto subscribed my name this seventh day of March, 1931.

HAROLD G. BAXTER. 

